Origin of cells

What is the spontaneous origin of cells?

The hypothesis that life originated from non-living matter through the formation of simple organic molecules, polymers, self-replicating molecules, and membranes.

What were the conditions on early Earth that supported the origin of life?

Limited oxygen, extremely high temperatures, no ozone layer (so high UV radiation), intense volcanic activity, and frequent asteroid bombardment.

What distinguishes inorganic molecules from organic molecules?

Inorganic molecules lack both carbon and hydrogen in the same molecule, are small, and associated with non-living matter. Organic molecules contain both carbon and hydrogen, are large, and are associated with living organisms.

What experiment demonstrated that carbon compounds could form from inorganic compounds?

The Miller-Urey experiment.

What are fatty acids and why are they important in the origin of life?

Simple amphipathic lipid molecules with a carbon chain and a carboxyl group; they can spontaneously form micelles or vesicles that resemble primitive membranes.

What is a micelle?

A spherical structure formed by fatty acids in water, with hydrophobic tails inward and hydrophilic heads outward.

What is RNA hypothesized to be the first genetic material?

Because RNA can both store genetic information and catalyze its own replication as ribozymes.

What are ribozymes?

RNA molecules that act as catalysts, similar to protein enzymes, capable of binding substrates and facilitating chemical reactions.

What is LUCA?

Last Universal Common Ancestor is the most recent ancestor from which all modern cells descended, likely an anaerobic, single-celled prokaryote living in extreme heat.

Where might LUCA have lived?

Near hydrothermal vents on the ocean floor, where hot mineral-rich water provided energy and materials for early life.

What are hydrothermal vents?

Openings in the ocean floor where heated water escapes from Earth’s crust, rich in minerals that support microbial life.

Why can’t viruses be considered living organisms?

They are not made of cells, do not grow, cannot independently replicate, and cannot perform metabolism.

What is one major problem with studying the spontaneous origin of cells?

The conditions that allowed life to arise no longer exist, so it’s nearly impossible to reproduce or find direct evidence today.

condition of early Earth

High temp, Volcanic activity,Intense UV radiation

The Miller-Urey experiment demonstrated that:

Carbon compounds can form from inorganic compounds

inorganic molecul

Small, without both carbon and hydrogen

What structure could primitive membranes have formed from?

Fatty acids

RNA

RNA can store information and catalyze reactions

What is the function of a ribozyme?

Catalyzes biochemical reactions like protein enzymes

LUCA is thought to have been:

An anaerobic prokaryote living near hydrothermal vents

What are hydrothermal vents?

Cracks on the ocean floor emitting hot, mineral-rich water

Why are viruses not considered living organisms?

They cannot replicate or metabolize on their own

What is one reason the spontaneous origin of life is hard to study today?

The early Earth conditions no longer exist